GE板形模型的功能及应用

梅钢热轧板厂于2002年引进了先进的凸度仪、平直度仪及GE板形模型,采用模型对窜辊量与弯辊力进行设定与闭环控制,板形质量有了量化指标与控制手段,通过几年的应用与实践,对板形模型的工作原理有了一定了解,文章论述了模型的设定策略、分配策略及控制策略,并阐述了该模型在负荷分配的优化、轧辊磨损量的优化、F4～F6工作辊原始辊型的优化及轧制计划的优化等方面的应用.     

Structure and electrochemical properties of titanate perovskite with in situ exsolution as a ceramic electrode material

Journal of Electroceramics - In this work, the structure and electrochemical properties of titanate ceramics with in situ Ni exsolution are investigated to identify the structure-performance...     

The potential use of <Emphasis Type="Italic">Fabaceae</Emphasis> lianas fibers in papermaking

The objective of this study was to anatomically characterize the fibers of nine species of Fabaceae lianas, to determine their potential in papermaking and to define which biometric parameters can be used to distinguish and identify individuals. The species presented average values of 76.81, 57.45, 42.55, and 1.81 for the felting index, wall fraction, coefficient of flexibility, and Runkel index, respectively. It is concluded that only M. ferox and M. madeirense can be recommended for papermaking.     

The impact of natural and artificial weathering on the visual,colour and structural changes of seven tropical woods

This study investigates the effects of wood weathering on changes in its macroscopic and colour characteristics in connection with changes in its molecular and anatomical structure. Seven hardwoods suitable for outdoor architecture—bangkirai, cumaru, cumaru rosa, ipé, jatobá, kusia, and massaranduba—were exposed to the exterior out of ground contact for 1–36 months according to EN 927-3, and for 1–12 weeks in Xenotest with water spraying according to partly modified EN 927-6. With prolonged weathering, the following changes occurred in the top surfaces of all tropical woods: (1) visual—creation of longitudinal macro-cracks, (2) spectrophotometry and CIE-L ^? a ^? b ^? —darkening in exterior exposure mainly due to pollutants, except for ipé, and vice versa lightening in Xenotest, as well as greening and blueing in both modes of exposure, (3) FTIR—faster decrease of guaiacyl than syringyl lignin, absolute decrease of conjugated and unconjugated carbonyl groups in the newly formed lignin-polysaccharide-extractive substrate in the photo-oxidized and washed-out cell walls, and decrease of cellulose crystallinity, (4) SEM—damaging of cell-walls by micro-cracks, and their degradation by thinning. Connections between changes of the individual characteristics of weathered woods, for example, between the colour (ΔE*, etc.) and the molecular structure (carbonyls, etc.), were also determined.     

Characteristics of cricket (<Emphasis Type="Italic">Gryllus bimaculatus</Emphasis>) chitosan and chitosan-based nanoparticles

The field cricket (Gryllus bimaculatus) is commonly consumed as food in different parts of the world. This study was performed to characterize the chitosan extracted from crickets and to assess its potential use to the growing functional market. The degree of deacetylation (DA), Fourier-transform infrared spectra, X-ray diffraction patterns, molecular mass, scanning electron microscopy spectra, and color were measured. Cricket chitosan nanoparticles were prepared, and the optimal conditions were identified. The molecular mass of the cricket chitosan was lower than that of commercial chitosan; however, the DA, FTIR, and XRD spectra were similar. The particle size (208.27 ± 3.47 nm), zeta potential (35.72 ± 1.29 mV), and polydispersity index (PDI: 0.27 ± 0.03) of the cricket chitosan NPs were superior to the commercial. Addition of NaCl reduced the cricket chitosan NPs size up to 15.5%. This finding is a novel trial to prove the availability of the insect chitosan with a low molecular mass as an active carrier source.     

闵行LNG汽车加气与灌装示范站低温预冷技术探讨

LNG(液化天然气)站的低温设备及工艺管道预冷是场站投产前的关键环节,以上海市闵行LNG汽车加气与灌装示范站工程站内低温设备及工艺管道预冷施工为例,分析阐述了LNG场站预冷的目的和原则,预冷的关键技术以及预冷后的注意事项等,并对工程进行总结归纳,对后续类似工程施工有一定指导作用。     

山西中部引黄工程小断面隧洞快速掘进施工方法

结合山西中部引黄工程的水文地质条件,分析了小断面隧洞快速掘进的施工难点及关键因素,并从施工部署、加宽段距离、工序衔接等方面,阐述了具体的施工方法,总结了施工安全、质量保障措施,实现了小断面隧洞的快速施工。     

土压平衡盾构机渣土运输系统设计

以某地铁线土压平衡盾构区间的渣土出运设计为例,介绍了土压平衡盾构的渣土运输系统,从渣土车选择、电瓶车运输能力选择等方面,阐述了电瓶车编组的方式,通过对其运输系统工效的分析,指出该工程采用的渣土运输设计方案,提高了盾构掘进速度,缩短了施工工期。     

A hybrid approach to detect crack parameters using measured natural frequencies in thin walled angle section steel beams

Present study outlines a hybrid approach using Finite Element Method (FEM)–Response Surface Method (RSM)–Genetic Algorithm (GA) to predict the crack parameters, namely crack position and crack depth ratio with the help of only the measured natural frequencies of cracked thin walled beams. Numerical experimental trials of cracked beams have been conducted based on design of experiment (DOE) approach using an improved Finite element model. The improvement has been achieved by consideration of warping stiffness in cracked angle section beam. Thereafter, regression analysis has been conducted to construct Response Surface Function (RSF). Optimum crack parameters were then calculated using GA by minimizing an objective function which has been formed as the root mean square (RMS) of the residuals between RSFs and measured frequencies. Results of the study indicate that, the proposed approach performs with excellent accuracy and it does not require the response of an uncracked beam as benchmark information.     

Evaluation of solar temperature field under different wind speeds for Shanghai 65 m radio telescope

The Shanghai 65 m radio telescope is currently the largest full range rotatable radio telescope in Asia. Gravity, wind and temperature are the three main factors which may have a bad effect on the reflector’s surface precision. To study the effect of the thermal deformation caused by daily non-uniform temperature fields on the surface precision of the main reflector, both the temperature field and its effect were studied in detail for two typical days (January 15th and July 15th). The method to simulate temperature fields was studied initially, considering heat conduction, solar radiation, shadowing, air convection, sky radiation and ground radiation. Then, an integral parametric thermal finite element model (FEM) of the telescope was established using the ANSYS thermal analysis module. Finally, the effect of non-uniform temperature fields on the surface precision of the main reflector was estimated in terms of the Root Mean Square (RMS) deformation based on temperature transient analysis. The proposed methods and conclusions drawn can provide valuable information for thermal design, thermal monitoring and thermal control of the Shanghai 65 m radio telescope and other similar giant antenna structures.